文章來源：微信公眾號 架構文摘

連線：https://mp.weixin.qq.com/s/Z9GsBru6866b4AY1fhWLrA

　　技術要點：Spring Boot的基本知識，Redis基本操作

　　首先是寫一個註解類：

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Retention(RUNTIME)
@Target(METHOD)
 
public @interface AccessLimit {

    /**
     * 秒，限制範圍
     */
    int seconds();

    /**
     * 最大請求數
     */
    int maxCount();

    /**
     * 是否需要登入
     */
    boolean needLogin()default true;
}

　　接著就是在Interceptor攔截器中實現：

import com.alibaba.fastjson.JSON;
import com.example.demo.action.AccessLimit;
 
import com.example.demo.redis.RedisService;
import com.example.demo.result.CodeMsg;
import com.example.demo.result.Result;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
 
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.OutputStream;
 
@Component
public class FangshuaInterceptor extends HandlerInterceptorAdapter {
 
    @Autowired
    private RedisService redisService;
 
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //判斷請求是否屬於方法的請求
        if(handler instanceof HandlerMethod){
            HandlerMethod hm = (HandlerMethod) handler;
            //獲取方法中的註解,看是否有該註解
            AccessLimit accessLimit = hm.getMethodAnnotation(AccessLimit.class);
            if(accessLimit == null){
                return true;
            }
            int seconds = accessLimit.seconds();
            int maxCount = accessLimit.maxCount();
            boolean login = accessLimit.needLogin();
            String key = request.getRequestURI();
            //如果需要登入
            if(login){
                //獲取登入的session進行判斷
                //.....
                key+=""+"1";  //這裡假設使用者是1,專案中是動態獲取的userId
            }
 
            //從redis中獲取使用者訪問的次數
            AccessKey ak = AccessKey.withExpire(seconds);
            Integer count = redisService.get(ak,key,Integer.class);
            if(count == null){
                //第一次訪問
                redisService.set(ak,key,1);
            }else if(count < maxCount){
                //加1
                redisService.incr(ak,key);
            }else{
                //超出訪問次數
                render(response,CodeMsg.ACCESS_LIMIT_REACHED); //這裡的CodeMsg是一個返回引數
                return false;
            }
        }
        return true;
 
    }
    private void render(HttpServletResponse response, CodeMsg cm)throws Exception {
        response.setContentType("application/json;charset=UTF-8");
        OutputStream out = response.getOutputStream();
        String str  = JSON.toJSONString(Result.error(cm));
        out.write(str.getBytes("UTF-8"));
        out.flush();
        out.close();
    }
}

　　再把Interceptor註冊到springboot中

import com.example.demo.ExceptionHander.FangshuaInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
 
    @Autowired
    private FangshuaInterceptor interceptor;
 
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(interceptor);
    }
}

　　接著在Controller中加入註解

import com.example.demo.result.Result;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
 
@RestController
public class FangshuaController {
 
    @AccessLimit(seconds=5, maxCount=5, needLogin=true)
    @RequestMapping("/fangshua")
    @ResponseBody
    public Result<String> fangshua(){
        return Result.success("請求成功");
    }
}